Subject: FAILED: patch "[PATCH] ceph: fix writeback_count leak in write_folio_nounlock()" failed to apply to 6.6-stable tree
To: vulab@iscas.ac.cn,Slava.Dubeyko@ibm.com,idryomov@gmail.com
Cc: <stable@vger.kernel.org>
From: <gregkh@linuxfoundation.org>
Date: Wed, 29 Jul 2026 15:46:47 +0200
Message-ID: <2026072947-gulp-passivism-4b27@gregkh>
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The patch below does not apply to the 6.6-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.6.y
git checkout FETCH_HEAD
git cherry-pick -x cbf59617cd715219e84c50d106a3d0e1e8ba054e
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2026072947-gulp-passivism-4b27@gregkh' --subject-prefix 'PATCH 6.6.y' 'HEAD^..'

Possible dependencies:


thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From cbf59617cd715219e84c50d106a3d0e1e8ba054e Mon Sep 17 00:00:00 2001
From: Wentao Liang <vulab@iscas.ac.cn>
Date: Thu, 4 Jun 2026 02:19:51 +0000
Subject: [PATCH] ceph: fix writeback_count leak in write_folio_nounlock()

write_folio_nounlock() increments fsc->writeback_count to track
in-flight writeback operations. On several error paths where the
function returns early (folio lookup failure, snapshot context
allocation failure, and writepages submission failure), the function
returns without calling atomic_long_dec_return() to decrement the
counter.

Each leaked increment keeps the counter above zero, which can prevent
the filesystem from cleanly unmounting or suspending writes.

Add atomic_long_dec_return() calls on all error paths that currently
return without decrementing the counter.

Cc: stable@vger.kernel.org
Fixes: d55207717ded ("ceph: add encryption support to writepage and writepages")
Signed-off-by: Wentao Liang <vulab@iscas.ac.cn>
Reviewed-by: Viacheslav Dubeyko <Slava.Dubeyko@ibm.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

diff --git a/fs/ceph/addr.c b/fs/ceph/addr.c
index 61bd6d92ff25..ecf33b66610c 100644
--- a/fs/ceph/addr.c
+++ b/fs/ceph/addr.c
@@ -790,6 +790,9 @@ static int write_folio_nounlock(struct folio *folio,
 				    ceph_wbc.truncate_size, true);
 	if (IS_ERR(req)) {
 		folio_redirty_for_writepage(wbc, folio);
+		if (atomic_long_dec_return(&fsc->writeback_count) <
+				CONGESTION_OFF_THRESH(fsc->mount_options->congestion_kb))
+			fsc->write_congested = false;
 		return PTR_ERR(req);
 	}
 
@@ -809,6 +812,9 @@ static int write_folio_nounlock(struct folio *folio,
 			folio_redirty_for_writepage(wbc, folio);
 			folio_end_writeback(folio);
 			ceph_osdc_put_request(req);
+			if (atomic_long_dec_return(&fsc->writeback_count) <
+					CONGESTION_OFF_THRESH(fsc->mount_options->congestion_kb))
+				fsc->write_congested = false;
 			return PTR_ERR(bounce_page);
 		}
 	}
@@ -847,6 +853,9 @@ static int write_folio_nounlock(struct folio *folio,
 			      ceph_vinop(inode), folio);
 			folio_redirty_for_writepage(wbc, folio);
 			folio_end_writeback(folio);
+			if (atomic_long_dec_return(&fsc->writeback_count) <
+					CONGESTION_OFF_THRESH(fsc->mount_options->congestion_kb))
+				fsc->write_congested = false;
 			return err;
 		}
 		if (err == -EBLOCKLISTED)